A quite frequent requirement is for having to remove a comparatively thin layer, which can be a layer of old lacquer or a damaged surface layer of the workpiece, from a planar workpiece, for example a table top, a door, a window frame or a parquet floor. Grinding machines, such as belt grinders or orbital sanders, have been employed for this purpose for a long time, but deeper scratches, dents or similar damage cannot be removed by these devices or they can be removed only with a large expenditure of time. The troubling generation of dust must always be tolerated with grinding work. The non-directional cutting edges of the grinding bodies have been shown to be disadvantageous for some types of application. In addition, under strong pressure it is particularly difficult for an untrained layman to guide a grinder, in particular a belt grinder, free of tilt and evenly, so that a level surface is generated. Processing by machining and cutting is given preference for the above mentioned reasons.
A manual planing machine with a roller-shaped planing tool is known from German Patent Publication DE 35 41 728 A1, . This machine defines an axis of rotation which extends parallel with the surface to be worked. However, manual planing machines of this type have the disadvantage that for all practical purposes they can only be moved in the circumferential direction of the planing roller, which extends parallel with the workpiece surface.
Finally, a device defining the species and available in commerce is known by the name "Lamello-Plano", in which a face milling cutter with an axis of rotation extending perpendicularly with the workpiece surface is provided. However, this tool is suitable and intended for a purpose different from that of the present invention. The tool is not intended to be employed for planar removal of a surface layer, but for the removal of a spatially limited overhang, such as is created, for example, by the insertion of a filler claw into a cut-out irregularity of the workpiece. The face milling cutter is disposed with the guide surface to be placed on the workpiece to be processed in an open-edged recess, so that the overhang extends into the cutting range of the face milling cutter in this open-edged recess. When using the known hand tool in accordance with this purpose, the face milling cutter is placed back away from the guide surface. This known hand tool has the further disadvantage that, aside from its purpose of use which is different from that of the present invention, working up to an area of the inner edge is not possible, because housing elements make the approach of the face milling cutter to an edge or step area impossible.
Surface milling cutters are also known which, however, are used in accordance with their purpose for machining surface profiles, such as grooves, dovetailed guides or the like, and furthermore do not permit surface treatment right up to a fold, and edge or a step.